Consumers have come to enjoy watching recorded television broadcasts through devices such as digital video recorders (DVRs) or personal video recorders (PVRs). These devices commonly contain local storage, such as hard drives or other memory, upon which users often record many hours of television content.
Because users expect the content they record onto their device's local storage to be safely stored such that it can be played back at any time, it can be distressing for users when the content is lost or becomes unplayable. However, such situations are common. For instance, a DVR's hard drive can fail and the content stored on it can be lost. As another example, when an existing DVR is replaced with a newer model, recorded content on the previous DVR is not automatically transferred to the new model and access to the recorded content is lost.
Some systems have been developed that allow recorded content on a DVR to be backed up or stored on an external drive, or to be uploaded to the cloud. However, content recorded by a DVR is often encrypted by the DVR with a device-specific encryption key that is unique to the particular DVR that recorded the content. In most existing systems it would be fruitless to load backed up encrypted content to a new DVR after an old DVR fails or is replaced, or to share recorded content with other devices, because the new DVR or other device does not have the same device-specific encryption key as the DVR that recorded the content and therefore could not decrypt the recorded content for playback. Even if the content could be transferred to a new device, in most existing systems it would need to be decrypted using the device-specific encryption key of the device that initially recorded the content, and then re-encrypted using the device-specific encryption key of the new device.
Some digital rights management systems have been developed, such as the Open Mobile Alliance Digital Rights Management (OMA DRM) specification, that provide a shared domain key to one or more devices tied to the same domain. In these systems a content provider initially protects media content with the domain key and provides the DRM-protected content to a client device in the domain. The receiving client device can then share the DRM-protected content with other client devices within the domain that also have the shared domain key. While these systems can allow multiple devices to share DRM-protected content that was initially received in protected form from a content provider, they do not allow content recorded by a DVR that was encrypted locally by the DVR to be shared with other DVRs or devices tied to the same subscriber account, or to be loaded onto a secondary or replacement device tied to the same subscriber account if the device that initially recorded and encrypted the content fails.